1. Technical Field
The present invention relates to a current detection apparatus mounted in a vehicle, such as a passenger car or a truck, for detecting a charge or discharge current of a battery.
2. Related Art
A known current detection apparatus, as disclosed in Japanese Patent No. 2704483, includes a circuit board (in the form of a printed-circuit board) provided with an electronic circuit thereon, and a casing accommodating the circuit board therein with a cover closing an opening of the casing to form an enclosure. In this current detection apparatus, each of a plurality of contact pins protruding from an inside surface of the casing and passing through a respectively corresponding through-hole arranged on the circuit board is soldered to a wiring on the circuit board to establish electrical connection between the contact pin and the wiring.
In soldering, which provides preferable electrical connection between each contact pin and the circuit board, the through-hole is fully filled with solder and a solder fillet covers the whole land on a rear-side surface opposite to an front-side surface (as a soldering surface) of the circuit board, resulting from a solder-rising phenomenon in which the solder rises along the through-hole from the front-side surface to the rear-side surface of the circuit board.
Unsuitable selection of a soldering condition or a flux material may lead to poor solder rise, i.e., less than 100% solder fill, as a kind of soldering failure. In the case of poor solder rise, a shortage of solder junction area may reduce thermal fatigue resistance and mechanical fatigue strength under heavy vibration at the solder junction. Hence, a soldered condition of the solder junction is of importance with respect to quality aspect of a product, i.e., a current detection apparatus. A decision as to whether each product is good or bad is made commonly by performing appearance (or visual) inspection for soldering failure after soldering.
In the disclosed apparatus, however, the circuit board lies lower than the level of a cover-mounting surface of the casing, and a clearance between the circuit board and an inside wall of the casing is small. This prevents the solder rise from being inspected visibly from the rear-side of the circuit board opposite to the front-side (on which side the cover is secured to the casing) after soldering. As an exemplary solution, a circuit-board receiver (corresponding to the element 11b in FIG. 2 of Japanese Patent No. 2704483) protruding from an inside bottom of the casing may be raised so that the circuit board mounted thereon lies higher than the level of the cover-mounting surface, thereby enabling appearance checking for soldering failure. This solution, however, leads to an increase in product size. In addition, in the recent automotive field, a larger interior space of a vehicle is ensured by downsizing an engine compartment, and the engine compartment is overcrowded by an increasing number of electronic devices for ensuring safety of the user. Therefore, the increase in product size, which may reduce mountability in the engine compartment and maintainability of the vehicle, is not desirable.
In consideration of the foregoing, it would therefore be desirable to have a current detection apparatus for enabling appearance inspection for soldering failure, such as poor solder rise, without increasing a product size.